Closed bearing frames or cylinder head covers principally offer the great advantage that they can be pre-assembled in a cost-effective manner. Moreover, they are relatively stiff and light, which is a decisive advantage in particular when used in motor vehicles. However, assembling a camshaft in such a closed bearing frame or such a cylinder head cover requires holding the individual components, for example cams, in their joining position and subsequent inserting a shaft tube of the camshaft, which is complicated and prone to error. Under certain circumstances, this can result in a high reject rate which, of course, has to be avoided. As an alternative, it is also conceivable to manufacture the camshafts separately, i.e., to join the cams and functional components separately on the shaft tube, as a result of which the reject rate can be reduced significantly. However, for a desired tunnel mounting, such completely pre-assembled camshafts require that comparatively large bearing openings are provided through which the camshaft together with the cams can be slid. Thus, the bearing diameter is significantly larger than the shaft diameter, which is contrary to the desire of minimizing friction. When using antifriction bearings, the mentioned friction problem is even more serious in the case of a large diameter of the bearing.